ABSTRACT. This work explores the implications of mounting and fixturing on piezoelectric resonators (PRs) for applications in inductorless DC-DC power conversion. From a scalability and packaging perspective, various mounting strategies are evaluated and impacts of solder bonding of PRs on performance and losses is quantified. COMSOL simulations are performed to verify shifts in PR resonance. Insights from fixturing are applied to assess the impact of mass augmentation strategies on mechanical losses and understand the feasibility of achieving higher power densities. Fixtured and augmented PRs are subsequently evaluated in a DC-DC converter to test the influence on converter efficiency.

ABSTRACT. Piezoelectric components have emerged as compelling alternative passive components for power electronics, with single-port piezoelectric resonators having demonstrated both high efficiency and high power density. However, numerous power electronics applications will require multi-port piezoelectric components, including piezoelectric transformers, and modeling of multi-port components is complex and requires cumbersome derivations. In this work, we derive a circuit model for multi-port piezoelectric components and provide multiple straightforward strategies for obtaining its model parameters. The proposed modeling strategy for multi-port piezoelectric components is validated experimentally for a 3-port radial mode piezoelectric component.

ABSTRACT. Power factor correction (PFC) maximizes grid utilization, yet PFC converters add significant volume to space-constrained applications. As such, the demand for higher power density PFC converters has led researchers to higher switching frequencies to shrink the boost inductor and EMI filter, but sublinear scaling of inductors to small volumes and high frequencies creates a bottleneck. Designing converters around piezoelectric resonators instead of inductors provides a path towards higher switching frequency and power density. While research has proven this idea for DC-DC converters, this paper presents analysis of circuit topologies and closed-loop control methods for piezoelectric resonator based PFC.

ABSTRACT. Miniaturization of power converters is limited by the declining performance of magnetic components at small sizes. Piezoelectric components offer an alternative energy storage mechanism that provides high power density and efficiency, particularly at miniature scales. This work extends the development of power converters based on piezoelectric resonators by presenting a novel isolated dc-dc piezoelectric-resonator-based topology that achieves galvanic isolation. Additionally, the converter achieves full resonant soft-switching and capacitor soft-charging, without the use of any magnetic components. A hardware prototype experimentally demonstrates a peak efficiency of 95.7% for 100V to 60V conversion and >88% efficiency over a power range of 1W to 13W.

ABSTRACT. Piezoelectric transformers (PTs) have emerged as promising alternative passive components for power conversion, offering high efficiency and high energy densities at small scales with galvanic isolation and/or inherent voltage transformation capabilities. However, the maximum efficiencies of PT-based converters have been limited to applications characterized by high load impedances, thereby confining their utility to a narrow subset of power electronics. In this work, we model, design, and demonstrate the use of higher resonant modes (overtones) in isolated PTs as a strategy for extending their high efficiency capabilities to lower load impedances. The 1st-overtone PT design is validated in a dc-dc converter prototype that demonstrates a peak efficiency of 97.1 % with a 2.5x reduction in optimal load impedance compared to fundamental-mode PT-based converters.

ABSTRACT. Passive power components such as magnetics, capacitors, and piezoelectric resonators have intrinsic characteristics that exhibit non-linear behaviors influenced by many factors such as temperature, dc-bias, memory effects, and waveform shapes. Traditional modeling methods are usually overly simplified and cannot fully capture their complex multi-scale, multi-physics behaviors. This paper presents the key concepts of time-domain foundation models for hysteresis transient in passive power components. The key properties of a time-domain foundation model include: 1) frequency agnostic, 2) has limited time horizon; and 3) can usually converge. We present an example neural network which is simple, robust, and accurate as one implementation of the foundation modeling framework.

ABSTRACT. As power targets and operating frequencies rise, losses in existing core materials increasingly bottleneck achievable power densities in medium-frequency (MF) transformers. Addressing this limitation requires the development of new magnetic materials tailored to the specific demands of MF transformers. To that end, we identify key material metrics that govern transformer performance and establish loss-driven guidelines to support the development, selection, and usage of magnetic materials for these applications.

ABSTRACT. Converters that incorporate split inductor designs demonstrate great potential for delivering high power while maintaining compact sizes, making them well-suited for data center applications. The input inductor buck converter, incorporating split inductors on the input side, represents the most fundamental topology with the split inductor design. This work presents a comprehensive analysis of the input inductor buck converter, deriving analytical expressions for bypass capacitor voltage and input inductor currents to facilitate the calculation of passive component volumes. The proposed model serves as a powerful design tool for designers to determine optimal passive component values based on specific requirements under various operating conditions.

ABSTRACT. This paper presents the circuits, systems, and design considerations of a 64× interleaved, four-phase, 17-level GaN-based Li-Fi transmitter achieving above-switching-frequency communication-over-power with PAPR=1.2 dB and SFDR=35 dB while driving 400 W LEDs with 95.5% efficiency. This performance is enabled by (1) fast GaN-based switching cells, (2) passive coupled inductor voltage balancing of multi-phase flying capacitor multilevel (FCML) topologies, (3) low-loss, high-density, high-frequency magnetics design with appropriate coupling, and (4) systematic considerations in device layout and control.

ABSTRACT. We model the performance of mm-scale optical power transmission to enable power electronics applications such as compact, high-efficiency optically-isolated gate drivers. We develop a model integrating the efficiency of the optical emitter and photovoltaic (PV) cell as well as the geometry of their optical coupling. A detailed analysis of the wavelength and intensity-dependent efficiency of light emitted diodes (LEDs), lasers, and PV cells provides benchmark data to understand the scaling limits of this system. We present a regime of sizes and power densities over which optical power transmission could outperform traditional magnetics in applications requiring high voltage isolation.

ABSTRACT. Wide bandgap (WBG) and Ultrawide bandgap (UWBG) power devices have marked strengths over traditional Silicon (Si) semiconductors. The key to harnessing these WBG/UWBG devices in medium/high voltage grid applications lies in designing the peripheral circuitry for control and gate driving, while maintaining galvanic isolation. Existing gate-driving solutions using transformers or separated coils are large and bulky, require shielding from EMI, and struggle with high common-mode dV /dt due to coupling capacitance. Optical gate triggering can simplify the system design, but current implementations using discrete devices suffer due to large parasitics. A heterogeneous photonic-electronic integrated solution will allow a step forward to develop compact, efficient, high-speed, and high-voltage WBG and UWBG converters. In this work, a discrete implementation of optical gate driving was successfully demonstrated at the frequency of 100 kHz. This proof of concept lays the groundwork and illuminates design considerations for heterogeneous integrated solutions using co-packaged photonic and electronic chips.

ABSTRACT. Accurate steady-state modeling is essential for analyzing and controlling resonant systems, including wireless power transfer (WPT) systems. Conventional first harmonic approximation (FHA) methods lack accuracy, while time-domain models require high computational costs and depend strongly on circuit topology and switching states. This digest presents an FFT-based steady-state simulation approach that supports various resonant topologies and system configurations and enables rapid identification of ZVS boundaries and assessment of power efficiency. Both simulation and experimental results validate its accuracy and show its potential for system design and optimization.

ABSTRACT. Accurate loss data is necessary for effective magnetic component design and evaluation – both of complete components and of core materials. While automated systems are available for core loss characterization at sub-MHz frequencies, existing resonance-based measuring methods for higher frequency characterization are labor intensive, typically relying on Fast Fourier Transform (FFT) and requiring human supervision to locate resonant points. In this paper, an integrated automated measurement system is proposed to eliminate dependence on FFT computations and manual adjustments to evaluate core losses in high-frequency magnetic components within seconds. The system uses high-frequency conditioning circuits to extract the magnitude and phase information of signals of interest. An embedded microcontroller in the system executes real-time algorithms to reach resonant points and collect core-loss-related data. The automatic test results on MHz magnetic materials align with datasheets, thus verifying the effectiveness of the proposed system.

ABSTRACT. This paper introduces an efficient algorithm that enables designers to quickly generate capacitor configurations and switch control signals for multi-phase Fibonacci converters. The algorithm provides a systematic approach, bridging the gap in existing methods and facilitating the practical implementation of high conversion-ratio SC converters. Measurement results of various experimental converters with two to six phases and up to five flying capacitors confirm the algorithm’s validity and practical applicability.

ABSTRACT. This paper presents a multiloop predictive control strategy for the Dual Active Bridge (DAB) converter, designed to achieve a fast dynamic response for both inductor current and output voltage. The proposed controller consists of an inner predictive current loop based on enhanced single-phase shift (ESPS) modulation using peak current sampling and an outer voltage loop that generates a reference for the current loop. A voltage disturbance observer is employed to estimate and compensate for the lumped disturbance, eliminating the need for a load current sensor. The performance of the proposed controller is validated through experimental results.

ABSTRACT. Abstract: A multiloop deadbeat control for voltage source converters (VSCs) with LC filters was introduced in [1]. However, we found that the inner current loop model in [1] does not fully capture the significant transient dynamics of the inductor current. We have proposed a revised model that more accurately reflects these dynamics. Based on the proposed inner loop model, an improved outer deadbeat voltage control has been developed.

ABSTRACT. This work proposes and analyzes a capacitively-isolated resonant dc/dc converter employing a flying capacitor multilevel (FCML) bridge leg to achieve a high step-down ratio. Limits on the maximum permissible isolation capacitance are identified through analysis of the constraint of touch current. Additionally, the FCML bridge leg is operated under zero-voltage switching, allowing operation at switching frequencies up to 1.3MHz. A 380V to 47V hardware prototype utilizing class Y2 safety capacitors is constructed and tested to a maximum output power of 680W.

ABSTRACT. This digest presents the design of an isolated full bridge DC--DC converter for converting a battery input (< 20 V) up to an output of 25 kV DC. The converter features a parallel voltage multiplier designed using custom high-voltage capacitors. A prototype (weight: 6.75 oz., volume: 7.5 in.^3) is presented along with experimental results under open-circuit conditions. This supply functions as a subcomponent of a larger DC supply (for future publication) which combines four parallel-driven 25 kV supplies, connecting their outputs in series to achieve a 100 kV DC output enabling the design of compact, lightweight neutron generators.

ABSTRACT. Electrical converters are becoming increasingly important. Especially if galvanic isolation is required, resonant converters are among the most often used converters. Many models are obtained using Fundamental Harmonic Approximation, Generalized Averaging Method and Extended Describing Function methods. It is in the nature of these techniques that, with increasing accuracy requirements, the model’s order increases and thus becomes more complex. To remedy this shortcoming, the following contribution presents a second order, discrete time, control oriented model for CL(L)LC Series Resonant Converters. Due to the model’s simple structure and its applicability below as well as above resonance frequency it can be used in a wide range of applications.

ABSTRACT. Load independence ensures stable output voltage or current and efficient power transfer across varying load conditions. Resonant converters leverage resonance to achieve this, making them ideal for such applications. This work presents general mathematical models for an n-mesh voltage-fed $T$ network, describing the transadmittance between any self-mesh current and input voltage. We derive general and particular solutions for even- and odd-numbered mesh networks, demonstrating that both can exhibit current- or voltage-source characteristics under suitable conditions. This systematic approach enables the design of resonant converters with tailored output characteristics. The results are validated through a 4-mesh voltage-fed DS-LCC wireless power systems.

ABSTRACT. Dual Path (DP) DC-DC converters use a parallel switched-capacitor (SC) branch to reduce DC current in the inductor. Past work has motivated the approach based on a stated advantage of being able to reduce overall loss while using relatively low quality (high resistance) inductors. This work explores a range of operating scenarios under which such claims are valid. We develop a unified model for all four 2:1 SC-based DP converters that factors in SC charge sharing loss, voltage and current ripple, and fixed-volume inductor scaling. We develop a set of constraints and criterion to compare the 2:1-based DP topologies to the conventional 3-level buck (3LB) converter to establish regimes where the DP value proposition is justified.

ABSTRACT. The development of future electric vehicles depends on high-performance power electronics. Aircraft require lightweight hardware with extreme efficiency, while volumetric density is important in traction applications. This work presents the design process of a flying capacitor multilevel inverter intended for lightweight, low-inductance electric machines. A detailed loss model is developed which includes the impact of flying capacitor voltage ripple. Along with a volume estimation framework, this enables multi-objective optimization to assess the impact of various design parameters. Key findings from the optimization are summarized. To validate this analysis, a 10-level FCML GaN-based hardware prototype is designed and fabricated, which is optimized for maximum power density. An innovative 3D-stacked layout is utilized, which makes efficient use of volume. This inverter achieves an unprecedented 800 kW/L volumetric power density and 250 kW/kg gravimetric power density, along with a peak efficiency of 97.34 % and THD < 5 %.

ABSTRACT. This digest presents the design of a Class-E power amplifier invariant to load changes for inductively heating a fluidized graphite bed. Experimental power output of an initial Class-E design was limited to 25 W by high conduction losses due to high input currents from driving a resistive load less than 5 Ω. A new design developed according to the temporal load impedance profile uses load transformation to both minimize input current and compress output network reactance. Thus, this digest presents simulation results of a 60 V 13.56 MHz amplifier with a maximum power of 125 W delivered to the load.

ABSTRACT. This paper presents a multiphase full-bridge inverter using air-core magnetics with an effective switching frequency of 8.2 MHz to assess the parallel interleaving and coupling performance for different phase winding configurations. We demonstrate the feasibility of extending phase-shifted interleaving to both sides of the full-bridge topology to reduce output current ripple. We also propose a four-winding toroidal inductor configuration which can simultaneously inversely couple phase windings on the same side of the full bridge as well as positively couple phase windings across the full bridge for additional common-mode current cancellation.

ABSTRACT. Hysteretic current control (HCC) of the inductor current in switched-mode power converters enables fast and direct control and requires high bandwidth isolated current sensing. However, analog-isolated Hall or TMR sensors consume a high power (typ.: 15 mW at 1.5 MHz). This work presents a digitally isolated HCC circuit using a shunt resistor, differential amplifier and two comparators with selectable reference values. A 1.2 MHz bandwidth HCC circuit was built and applied to a half-bridge converter, consuming only 2.3 mW during operation (from which 1 mW are from an isolated 5 V power supply).

ABSTRACT. Accurate magnetic modeling at high frequencies is critical for designing compact, high-efficiency power electronic converters. Previous work developed a physics-based core loss model using the Landau-Lifshitz-Gilbert (LLG) equation to analyze nonlinear magnetic properties, including core loss and permeability variations. In this study, the hethe spherical form of the LLG equation is employed, significantly reducing computational effort compared to the cartesian formulation. Furthermore, precessional motion is eliminated by simplifying the full LLG equation to a reduced LLG equation, where only the dθ/dt term is retained, and dφ/dt=0 is enforced. As a result, the model in this paperThis resulting model focuses solely on magnetization switching, which governs hysteresis behavior. The findings in this work are based on a single-domain model, demonstrating the effectiveness of the simplified LLG equation in preserving magnetization reversal behavior. Future work will aim to extend this approach to macroscale core loss modeling.

ABSTRACT. Classic control system approaches sometimes lack a transparent and convenient process. The designer needs to simultaneously observe multiple criteria including stability, stability margins, transient response indices, and steady-state errors. The approaches based on state-space models, on the other hand, suffer from lack of a systematic procedure to choose closed-loop poles, or to choose optimal control weight matrices. This paper presents a control structure and a design procedure to address these issues. The proposed approach is applicable to both single-input single-output (SISO) and multi-input multi-output (MIMO) control systems. It system enjoys systematic design and robust performances with controlled transient responses.

ABSTRACT. This work presents a dynamic phase control method for a multiphase modular buck converter aimed at applications aiming for zero downtime, such as data centers. A key feature of the work is that the converter design has a switchable modular power stage that can be installed or removed while the converter is still operating. This allows converters to stay online while a sub-module can be repaired or upgraded to higher power. To achieve this, a control strategy has been developed that allows for an arbitrary number of converter phases that dynamically adapt to different numbers of phases.

ABSTRACT. Aiming to improve the performance of general buck converters in complex disturbance environments, an adaptive integral-type non-singular terminal sliding mode (AINTSM) control method with zero-crossing control gain is proposed in this paper. In contrast to conventional linear sliding mode (LSM) and NTSM methods with fixed gain, the proposed AINTSM approach maintains a simple structure while effectively mitigating chattering due to the adaptive gain and overcoming singularity issues associated with global convergence. Initially, an accurate model is developed incorporating bounded matched and mismatched disturbances; Subsequently, an AINTSM controller is designed by integrating an integral error regulation with an adaptive zero-crossing gain, and global finite-time convergence is achieved by Lyapunov-based analysis; Furthermore, the impact of variations in control parameters on the system's dynamic and static performance is analyzed, with stability conditions for the AINTSM parameters clarified by phase trajectory analysis. Finally, numerical simulations and experimental findings under parameter disturbances verify the efficacy of the proposed method.

ABSTRACT. This paper introduces a novel curvature-based ripple correlation control (RCC) technique for maximum power point tracking (MPPT) in photovoltaic (PV) systems. RCC has become a prominent MPPT method due to its straightforward implementation, high accuracy, and quick asymptotic convergence. It effectively tracks the maximum power point (MPP) of PV systems amidst swift changes in solar irradiance and temperature. The curvature of the power-voltage curve provides essential insights into the power output behavior of PV panels in response to voltage fluctuations. Specifically, the curvature offers a critical indication of the system's proximity to the MPP. This information is crucial for optimizing the control gain of the RCC to enhance both dynamic and steady-state performance. Simulation and experimental results corroborate the theory proposed in this paper and validate its contributions.

ABSTRACT. This paper proposes a specialized design for inductively-coupled-plasma generator without matching-network. Plasma’s nature, negative-differential-resistance, and soft-switching of DC-AC converters are considered with extensive comparisons of circuit topologies. Voltage-driven series-resonance frequency-tracking scheme showed great suitability.

ABSTRACT. The integration of energy storage into renewable energy systems helps address the growing demand for electricity and the intermittency of power generation. Incorporating batteries into photovoltaic microinverters improves grid power stability but increases system complexity, requiring a bidirectional DC-DC converter for efficient battery management. This study compares the strategies between switching frequency control and charge control for bidirectional CLLC resonant converters to enable rapid battery charging/discharging transitions.

ABSTRACT. This digest presents the design and implementation of a closed-loop control to synchronize the switching actions of an active rectifier (AR) on-board the receiver of a wireless drone charger with the offboard transmitter induced magnetic field. A discrete time model of the wireless drone charger is used to model the synchronization dynamics. A compensator is designed to achieve stable performance over the full load range. The synchronization controller is designed to achieve a stable transition from passive to active rectification, and to reduce susceptibility to noise. To validate the control design, a GaN-based prototype is constructed and stable startup and low-noise synchronization experimentally demonstrated.

ABSTRACT. This digest discusses the reverse power flow issue in wireless battery charging for drone applications. The charger, which incorporates an active rectifier at the receiver end, is susceptible to reverse power flow during the constant voltage charging mode. To resolve this, a cascaded Constant Current (CC)-Constant Voltage (CV) control approach is employed. The charger is designed for a 6S LiPo battery pack, consisting of six series-connected cells, with no cell voltage balancing circuits. The proposed control scheme monitors the voltage of each cell and ensures that the appropriate charging mode is selected to avoid overcharging any single cell. The sensing, monitoring, and control mechanisms are detailed with relevant simulation and experimental results for a 200 W wireless charger

ABSTRACT. This paper presents a mathematical formulation of the Photovoltaic Exponential Model (PVEM), which describes the electrical characteristics of photovoltaic (PV) modules. In the paper, the PVEM is derived from fundamental physical principles and known boundary conditions while balancing mathematical rigor and clarity. The study demonstrates the PVEM's practical utility by deriving through the model an analytical solution for the maximum power point (MPP) using the Lambert W function, a significant departure from traditional numerical methods. This work also provides an analysis of the elusive characteristic constant 'b', clarifying its existence and impact on the MPP by demonstrating plots with differing values of 'b'.

ABSTRACT. Dynamic capacitive wireless charging enables electric vehicles (EVs) to charge in motion, eliminating range limitations, charging time, and reducing EV costs with smaller batteries. This digest explores cost, weight, and size reductions in capacitive charging pads to enhance adoption. First, alternative coupling plate materials and thicknesses are examined to lower cost and weight. Additionally, optimizing the dielectric layer with strategic cutouts further reduces these factors. The proposed design achieves a 41% cost reduction, 76% weight decrease, and 37% height reduction while maintaining performance. Finally, two 6.78-MHz 12-cm air-gap 1-kW prototypes validate the effectiveness of these optimizations.

ABSTRACT. All magnetic components have parasitic capacitance that limits performance. This work derives closed-form mathematical expressions to model parasitic capacitance and applies them in a multi-objective optimization method to assess design trade-offs in toroidal inductors with single-layer windings. The model is validated through Finite Element Analysis (FEA), showing good agreement.

ABSTRACT. This digest presents a novel full-state feedback (FSF) controller for compensating changing coupling variations in dynamic capacitive wireless power transfer (WPT) systems utilizing an active variable reactance (AVR) rectifier. The AVR rectifier enables continuous compensation, allowing the WPT system to maintain high-efficiency power transfer at a fixed frequency by appropriately distributing power between its two branches. Conventional PID control approaches are suboptimal for the AVR rectifier due to the higher-order system dynamics, nonlinearities, and cross-coupling between control loops. In contrast, the FSF control strategy presents an optimal and robust way to control higher order multi-input multi-output systems like the AVR rectifier. A state-space model is developed for the AVR rectifier, and the FSF controller is designed based on this model. To validate the proposed approach, a 13.56 MHz 100-W capacitive WPT system with an AVR rectifier is built and tested. The controller’s effectiveness is demonstrated through both simulations and experiments on the hardware prototype.

ABSTRACT. Series-input, parallel-output power converters are an effective solution for applications requiring high energy density and large conversion ratios. Hybrid switched-capacitor topologies are a compelling alternative to the traditional magnetics-based topologies commonly used in stacked converters. One required feature of these series-input, parallel-output converters is the ability to achieve electrical isolation between the input and output grounds. Capacitor-based isolation enables low passive volume, indicating the potential for use in weight- and volume-constrained application spaces. This digest presents a capacitively-isolated variant of the series-parallel hybrid switched-capacitor converter capable of at- and above-resonance operation. Generalized equations for the mid-range voltages of the flying capacitors and phase duration equations are provided. Experimental results of a prototype of the 4:1 capacitively-isolated series-parallel converter validate the analysis.

ABSTRACT. This paper presents a novel control technique, Integral Cycle Mode (ICM), for RF inverters used in plasma generation applications. Conventional control methods such as phase-shift, DC voltage, and frequency control, face trade-offs between dynamic response, soft-switching range, and system complexity. The proposed ICM method achieves fast dynamic performance comparable to phase-shift control while ensuring soft-switching across a wide load range through maintaining inductive load operation and frequency tracking. This approach eliminates the need for additional hardware or complex interleaving schemes. The effectiveness of ICM is validated through both simulation and experimental results, demonstrating its potential for semiconductor process.

ABSTRACT. An isolated flying-capacitor (FC) based, quasi-resonant (QR), hybrid step-up converter topology capable of producing voltage conversion ratios exceeding 50x, while maintaining relatively high-power processing efficiency at sub-1W power levels, and a complementary mixed-signal controller are presented. By resonantly charging and discharging a small flying capacitor on the secondary side, through a specific control scheme: (a) load-independent soft-switching is achieved on all the switches on the secondary side, (b) volage stress across the primary switch has been reduced to just the input voltage, (c) operation independent of input-to-output voltage conversion ratio. With significant reduction in switching losses, and isolation, the converter is well suited for low-power applications, where switching losses would otherwise be dominant. The operation of the converter is experimentally verified using a discrete prototype with input voltages 3 V to 3.6 V, output voltages up to 300 V, and output power as low as 50 mW.

ABSTRACT. This paper proposes a model reference correction method for discontinuous current mode (DCM) grid-tied inverters to improve average current regulation and zero-voltage switching (ZVS) accuracy. The method addresses errors due to deviations in the inductor value in the control system and their impact on the grid-side current. By integrating grid-side current data with a DSP-based valley sensing module, these errors are detected, enabling model reference correction. This approach reduces the need for precise circuit parameter knowledge, simplifying the design while maintaining high performance.

ABSTRACT. Classical transient stability assessment methods, such as the equal area criterion and Lyapunov energy function-based approaches, have long been used to analyze the large-signal stability of power systems. However, when applied to grid-forming (GFM) inverters, these methods fail to account for key inverter-specific dynamics, including damping effects, reactive power-voltage interactions, and the influence of current limiters. In recent literature, an alternative equivalent circuit-based energy function approach has been proposed to provide a more accurate transient stability assessment for GFM inverters. In this paper, we demonstrate how this circuit-based approach emerges from fundamental energy function principles and show how it addresses the key limitations of classical transient stability assessment methods. Numerical simulations validate the effectiveness of the equivalent circuit-based energy function in characterizing the transient stability of GFM inverters.

ABSTRACT. AC-DC converters with cascaded units are gaining popularity for medium voltage (MV) level grid connection however, they can get damaged due to high inrush currents during the start-up sequence if there is no soft-start method implemented during the start-up of each stage. Moreover, in MV systems, measurement of grid voltage is not only challenging, it is also not available at each unit in the cascaded stack and hence needs to be communicated. This becomes cumbersome and unreliable when the number of units is high, due to wiring and isolation requirements, communication bus failure, expensive optical fibers etc. In this article, we address these issues and challenges by proposing a decentralized soft-start-up procedure for a cascaded ac-dc system composed of Cascaded H-Bridge (CHB) and Quad-Active Bridge (QAB) converters. The proposed soft start-up sequence charges up the QAB output dc-link by limiting the inrush current and achieves grid-synchronization of the CHB stage in a decentralized fashion, which does not require any grid voltage measurement or phase locked loops (PLL) as used in conventional methods. The stability analysis and simulation results of the proposed start-up method for a system of 5 series connected ac-dc units have been presented.

ABSTRACT. Recently, the Laboratory for Energy and Switching-Electronic Systems (LESES) at the University of Illinois Chicago (UIC) has demonstrated a new approach to compromise the performance and stability of power-electronic systems (PES) such as inverters, solid-state transformers (SSTs) using side-channel noise intrusion (SNI). In this manuscript, we outline what the SNI phenomenon is, how it is realized, and how it distinguishes from other apparently related cybersecurity threats. Finally, we also illustrate the effects of SNI on the performance of an inverter and an ac/ac SST and how cyber-resilience can be achieved against such intentional intrusions.

ABSTRACT. This paper presents a cost-effective single-phase to split-phase inverter with a reduced switch count, achieving grid-interactive performance while maintaining operational efficiency. The proposed system integrates an Andronov − Hopf oscillator-based secondary controller, which inherently embeds a nonlinear resistive droop architecture, ensuring rapid dynamic response. A Lyapunov energy function-based primary control enhances transient stability and regulation, while an internal model-based point of common coupling voltage estimation enables cost optimization without additional sensors. Equipped with advanced grid support functionalities, the inverter facilitates seamless distribution system operation with enhanced robustness. The effectiveness of the proposed architecture and control strategy is validated through MATLAB/Simulink and PLECS simulations, demonstrating its feasibility for high-performance grid-supportive applications.